In a two-dimensional fluid corotating with a spherical surface, like
the Earth's atmosphere, the vorticity of the fluid depends on the
latitude: the vorticity is largest in the north and south polar
regions while it vanishes near the equator.
This vorticity gradient, combined with the Coriolis effect, produces
intriguing fluid phenomena, such as the dynamics of the meandering jet
stream in the Earth's atmosphere.
In 1939, Rossby and his collaborators identified that such waves under
the vorticity gradient and Coriolis effect can explain several
meteorological observations [1]}, which are nowadays called
Rossby waves [2]}, [3]}.
In 1940, Haurwitz provided the eigenmodes of Rossby waves on a
rotating spherical surface [4]}, which are referred to as
Rossby-Haurwitz (RH) waves.
